F.C. Stern A Study of the Genus Paeonia

Section Paeon Subsection Dissectifoliae

peregrina group.—This group contains only the one species, P.peregrina. Although it is in the dissectifoliae subsection, with leaflets deeply cut into segments, it can be easily distinguished from all other species in this subsection and also from all other paeonies by its segments, [end page 028] which are lobed and coarsely toothed at the apex, and also by its concave petals. P.peregrina is confined to the Balkans and to the Turkish seaboard near Smyrna. It is a tetraploid. Clusius first drew attention to this great red paeony in the 16th century and described it as P.byzantina. Stapf (1918) gave its history. There has been much confusion over the name P.peregrina which has been given to several distinct species. The nomenclature of this species and an account of the confusion which has grown up around the name is given on page 127.

officinalis group.—This group of paeony species is distinguished by having the leaflets deeply cut into twenty-one or more segments which are elliptic, oblong-elliptic or oblong. The species and varieties in this group extend from Crete up the Dalmatian coast from Albania, and from northern Italy and Switzerland south-west through the south of France to the centre of Spain. They differ from each other in the size of the leaf-segments and in the amount of hairiness on the leaves and carpels.

The best known species is P.officinalis. This name has been used very often in the past for several different species but has now been restricted to the wild paeony found most commonly in northern Italy. P.officinalis is also found in Albania and on the Dalmatian coast and in Switzerland. These paeonies of northern Italy and the south of France are far the most difficult of all the species to disentangle and the many names that have been bestowed on them in the past have added to the difficulty. If a bird's-eye-view is taken of the whole group, it becomes clear where each of the species and varieties are located and how they dovetail into each other's territories.

P.humilis Retz. is the most westerly species of this group, being indigenous to the centre of Spain, extending to the borders of Portugal ; it has leaf-segments which are shorter and broader than are the leaf-segments of P.officinalis, and the carpels are glabrous or sub-glabrous. It extends from Spain to the Montpellier district in southern France, where it dovetails into another form which was named P.paradoxa by Anderson (1817). As this plant only differs from P.humilis by its tomentose carpels and villose stem, it is treated as a variety—P.humilis var. villosa. The variety villosa extends from Montpellier to the north-west of Lyons and south to the Mentone district, where it meets another paeony to which the name villosa was given by Desfontaines (1804), but as he never described the plant his name has no validity. P.humilis var. villosa is also found in the Abruzzi in the centre of Italy without apparently any connecting link between this district and the south of France.

The paeony of the Mentone district is merely a form of P.officinalis, differing from the northern Italian form of P.officinalis in the hairiness of the petiole and the undersides of the leaves. The degree of hairiness on the underside of the leaves and on the stem in different districts is also found to vary among plants of P.arietina. All wild specimens of P.officinalis have some hair on the underside of the leaf, but some garden-grown specimens are glabrous; these latter have been known by the name of P.festiva.

Anderson named a paeony of the Officinalis group P.mollis from a specimen grown in a garden; it has been suggested that this plant also came from these districts of southern France. It differs from the other paeonies in the group by its upright stalk, its sessile leaves and a flower which is subsessile with a short stalk, making the flower look as if it were sitting down among the leaves. No wild specimen of this plant appears to be preserved in herbaria but only those from gardens, so it is likely that this plant is of garden origin and is not found in a wild state : a white-flowered form has been named P.sessiliflora. [end page 029]

P.Clusii, from the island of Crete, is another member of the Officinalis group, differing from P.officinalis by possessing smaller and narrower leaf-segments and white flowers. This species, which as far as is known is only found in Crete and the island of Karpathos, lying between Crete and Rhodes, is a diploid, while P.officinalis and P.mollis are tetraploids ; the chromosome numbers of P.humilis and its variety villosa are not yet known.

tenuifolia group.—P.tenuifolia might be included in the Officinalis group because the leaflets are cut into many segments, but perhaps it should be made into a group of its own as it occupies an isolated position with its very finely linear segments 1.25-2 mm. wide. These give this paeony a unique appearance quite unlike that of any other species. It is a diploid and has fairly wide distribution from Hungary to the Crimea and Caucasus ; it is also found in Bulgaria and Armenia.

anomala group.—The Anomala group contains two species and their varieties, P.anomala, P.anomala var. intermedia, P.Veitchii and P.Veitchii var. Woodwardii; their leaves are much [end page 30] dissected into a number of linear or very narrowly oblong segments. This group has a special character, to which Huth drew attention when writing of P.anomala, i.e., the presence of an uninterrupted line of delicate small hairs (which are only just visible through a lens) along the main veins on the otherwise glabrous upper side of the leaves.

P.anomala and its variety extend from the Kola Peninsula in the Arctic Circle through N.E. European Russia, over western Siberia to the Altai Mountains and into Turkestan. The distinction between P.anomala and the variety intermedia lies in the densely tomentose carpels of the latter.

P.Veitchii and its variety are confined to a comparatively small district in western China in the provinces of Szechwan, Kansu and Shensi ; they are distinguished by bearing several flowers on each stem, which character separates them from P.anomala and its variety, which have only one flower on each stem.

There are several points of special interest in this group of paeonies. They all show extraordinary variation in the breadth of the leaf-segments, ranging from 3 mm. to 15 mm. Again, although pairs of species, one with glabrous and the other with tomentose carpels, are a common phenomenon among paeonies, usually each such variety is confined to a separate district, but in the case of P.anomala and the variety intermedia, both appear to be growing together in most of the locations in which they have been found.

It has been suggested that the Chinese species, P.Veitchii and its variety Woodwardii, might be considered varieties of P.anomala, but I have kept them separated since the character of bearing more than one flower on each stem seems to me to be one of specific value. The habit of growth and different time of flowering further separates P.Veitchii and its variety from P.anomala and its variety.

All the species belonging to this group are diploids. [end page 31]

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